In manufacturing processes for image sensors according to a related art, methods for forming microlenses generally involve performing a photolithography process using a special photoresist for microlenses, and then performing reflowing process. With recent developments in image sensor technology, the thicknesses of microlenses are progressively decreasing.
However, when photoresists currently in use are subjected to the related art processing, striation occurs, causing reduced pixel region uniformity. The main cause for this limitation is the occurrence of a planar offset between a scribe line and a pixel region.
Specifically, in the related art, when striation due to a height difference at the border between a scribe line and a pixel region occurs, the thicknesses of microlenses in the pixel region are different, causing the focal points of the microlenses to be different.
In particular, while this limitation presents little variance at the center of the pixel region, the occurrence of cross talk becomes more pronounced toward the edge of the pixel region, resulting in the generation of noise and reduced sensitivity.